Parameter determination method of toroidal inductor, toroidal inductor and buck-boost converter

Abstract

The application relates to energy storage device technology. The application provides a parameter determination method of a ring inductor, the ring inductor and a step-up and step-down converter, and aims to solve the problem that in the design process of a traditional step-up and step-down converter, there is no energy storage inductor designed completely for the working condition of the step-up and step-down converter. The parameter determination method of the ring inductor comprises the following steps: determining target electrical parameters and a target inductance of the step-up and step-down converter, determining the number of turns according to a primary selected magnetic core and the target electrical parameters, calculating the wire diameter according to the number of turns, and verifying. The ring inductor is more suitable for the corresponding step-up and step-down converter.

Description

Technical Field

[0001] This application belongs to the field of energy storage equipment technology, and in particular relates to a method for determining the parameters of a toroidal inductor, a toroidal inductor and a buck-boost converter. Background Technology

[0002] Currently, when designing circuits that include buck-boost converters, it is necessary to select appropriate energy storage inductors based on different application scenarios. If the energy storage inductor is not selected appropriately, it can lead to output abnormalities in the buck-boost converter during actual use. However, traditional buck-boost converters do not have energy storage inductors specifically designed for their operating conditions.

[0003] Therefore, in the traditional buck-boost converter design process, there is a problem that the energy storage inductor is not designed specifically for the operating conditions of the buck-boost converter. Summary of the Invention

[0004] The purpose of this application is to provide a method for determining the parameters of a toroidal inductor, a toroidal inductor, and a buck-boost converter, in order to solve the problem that in the traditional buck-boost converter design process, there is no energy storage inductor designed specifically for the operating conditions of the buck-boost converter.

[0005] In a first aspect, embodiments of this application propose a method for determining the parameters of a toroidal inductor, the method comprising:

[0006] The target inductance under various current conditions is determined based on the target electrical parameters of the buck-boost converter, including the target ripple current.

[0007] Obtain the core parameters of the initial core of the toroidal inductor, and determine the number of turns of the toroidal inductor based on the core parameters and the target electrical parameters;

[0008] The wire diameter is calculated based on the number of turns of the toroidal inductor, and the initial inductance is calculated based on the core parameters, the number of turns, and the wire diameter of the toroidal inductor.

[0009] The difference between the initial inductance and the target inductance is obtained. When the difference satisfies the preset difference, the ripple current of the toroidal inductor under different operating conditions of the buck-boost converter is obtained.

[0010] When all the ripple currents meet the target ripple current of the buck-boost converter, the toroidal inductor is used as the target toroidal inductor.

[0011] In one embodiment, determining the number of turns of the toroidal inductor based on the core parameters and the target electrical parameters includes:

[0012] Based on the core parameters and the target electrical parameters, obtain a mapping table between the loss and the number of turns of the toroidal inductor;

[0013] The number of turns of the toroidal inductor is determined according to the mapping table between losses and the number of turns.

[0014] In one embodiment, determining the mapping table between the loss and the number of turns of the toroidal inductor based on the core parameters and the target electrical parameters includes:

[0015] Get the preset window coefficient;

[0016] Calculate the copper loss of the wires on the toroidal inductor at different numbers of turns based on the preset window coefficient, the magnetic core parameters, and the target electrical parameters;

[0017] Calculate the magnetic loss of the magnetic core at different numbers of turns based on the magnetic core parameters and the target electrical parameters;

[0018] The loss of the toroidal inductor is obtained by calculating the sum of the copper loss and the magnetic loss.

[0019] Based on the copper loss, the magnetic loss, and the total loss, a mapping table between the loss and the number of turns is determined.

[0020] In one embodiment, the target electrical parameters include:

[0021] Input voltage range, maximum input current, maximum charging power, output voltage range, maximum charging current, switching frequency, or target ripple current are one or more of the following:

[0022] The determination of the target inductance under various current conditions based on the target electrical parameters of the buck-boost converter includes:

[0023] Based on the input voltage range and the output voltage range, calculate the inductance and inductor current flowing through the inductor corresponding to the target ripple current output by the buck-boost converter in buck conversion mode and buck conversion mode, respectively.

[0024] Under the same inductor current, obtain the maximum value of the inductance, and use the maximum value as the target inductance.

[0025] In one embodiment, the parameter determination method further includes:

[0026] Obtain the core parameters for each magnetic core;

[0027] To obtain the DC bias resistance capability of each magnetic core under the same parameters;

[0028] The magnetic core with the greatest resistance to DC bias is selected as the initial magnetic core.

[0029] In one embodiment, the parameter determination method further includes:

[0030] If the difference does not meet the preset difference, or if there is a ripple current that does not meet the target ripple current, the initial magnetic core is replaced, and the steps of obtaining the magnetic core parameters of the initial magnetic core of the toroidal inductor and determining the number of turns of the toroidal inductor based on the magnetic core parameters and the target electrical parameters are executed.

[0031] Alternatively, if the difference does not meet the preset difference, or if there is a ripple current that does not meet the target ripple current, the number of turns of the toroidal inductor is changed, and the steps of calculating the wire diameter based on the number of turns of the toroidal inductor and calculating the initial inductance based on the core parameters, the number of turns, and the wire diameter are performed.

[0032] In one embodiment, calculating the wire diameter based on the number of turns of the toroidal inductor includes:

[0033] Obtain the window area of ​​the magnetic core of the toroidal inductor;

[0034] Get the preset window coefficient;

[0035] The wire diameter is calculated based on the window coefficient, the window area, and the number of turns.

[0036] In one embodiment, the parameter determination method further includes:

[0037] Calculate the maximum current density of the toroidal inductor based on the wire diameter and the target electrical parameters;

[0038] When the maximum current density is greater than the preset maximum current density, the initial magnetic core is changed and / or the number of turns is changed.

[0039] Secondly, this application provides a toroidal inductor for use in a buck-boost converter, wherein the toroidal inductor is designed and manufactured according to the parameter determination method described above.

[0040] Thirdly, embodiments of this application propose a buck-boost converter, including the toroidal inductor as described above.

[0041] The beneficial effects of the present invention embodiment compared with the conventional technology are as follows: the above-mentioned method for determining the parameters of the toroidal inductor, when calculating the number of turns, refers to the target electrical parameters of the buck-boost converter, and also verifies the obtained toroidal inductor through the target ripple current of the buck-boost converter, so that the designed toroidal inductor is more suitable for the buck-boost converter, and the method is simple and easy to use. Attached Figure Description

[0042] Figure 1This is a schematic diagram of the buck-boost converter provided in the embodiments of this application;

[0043] Figure 2 A flowchart illustrating the method for determining the parameters of a toroidal inductor provided in an embodiment of this application;

[0044] Figure 3 for Figure 2 A flowchart illustrating steps S101 of the method for determining the parameters of a toroidal inductor;

[0045] Figure 4 for Figure 2 A flowchart illustrating the process of determining the number of turns of a toroidal inductor based on core parameters and target electrical parameters in the parameter determination method for a toroidal inductor.

[0046] Figure 5 for Figure 4 A flowchart illustrating steps S1021 of the method for determining the parameters of a toroidal inductor;

[0047] Figure 6 A graphical schematic diagram of the mapping relationship table between loss and number of turns in the method for determining the parameters of a toroidal inductor provided in the embodiments of this application;

[0048] Figure 7 for Figure 2 Another flowchart illustrating the method for determining the parameters of a toroidal inductor;

[0049] Figure 8 for Figure 2 A flowchart illustrating the process of calculating the wire diameter based on the number of turns in a toroidal inductor, as part of the parameter determination method.

[0050] Figure 9 This is a schematic diagram showing the relationship between the inductance of magnetic cores with two initial permeabilities and the inductor current flowing through the inductor in the embodiments of this application.

[0051] Figure 10 for Figure 2 Another flowchart illustrating the method for determining the parameters of a toroidal inductor;

[0052] Figure 11 for Figure 2 Another flowchart illustrating the method for determining the parameters of a toroidal inductor. Detailed Implementation

[0053] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0054] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0055] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0056] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0057] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0058] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrases "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0059] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0060] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0061] Figure 1 A schematic diagram of the buck-boost converter provided in an embodiment of this application is shown. For ease of explanation, only the parts related to this embodiment are shown, and are described in detail below.

[0062] The buck-boost converter 101 includes an energy storage inductor L, a first switch Q1, a second switch Q2, a third switch Q3, and a fourth switch Q4.

[0063] The input terminal of the buck-boost converter 101 is connected to the first terminal of the first switching transistor Q1. The second terminal of the first switching transistor Q1 is connected to the first terminal of the second switching transistor Q2, and also connected to the first terminal of the energy storage inductor L. The second terminal of the second switching transistor Q2 is grounded. The input terminal of the buck-boost converter 101 is used to connect the input voltage V. in .

[0064] The first terminal of the fourth switch Q4 is grounded. The second terminal of the fourth switch Q4 is connected to the first terminal of the third switch Q3 and to the second terminal of the energy storage inductor L. The second terminal of the third switch Q3 is connected to the output terminal of the buck-boost converter 101 for output voltage V. o .

[0065] In this embodiment, the energy storage inductor L of the buck-boost converter 101 is a toroidal inductor. When the parameters of the toroidal inductor are unsuitable, the following situations may occur: 1. If the inductance of the energy storage inductor is too small, the ripple current and losses will be large, affecting the overall current efficiency and temperature rise. 2. If the magnetic core of the energy storage inductor is unsuitable, such as when the inductance of the selected core is smaller than the required inductance for a specific current, the output voltage of the overall circuit may be incorrect, and the ripple current may be too large. 3. If the coil wire diameter of the energy storage inductor is too small, the current density will increase, the coil temperature will increase, and the copper loss will also increase. 4. If the number of coil turns of the energy storage inductor is too large, the cost will increase, and the losses will also increase. 5. If the number of coil turns of the energy storage inductor is too small, the inductance of the energy storage inductor cannot be guaranteed, and the losses may increase.

[0066] Figure 2 A schematic flowchart of a method for determining the parameters of a toroidal inductor provided in an embodiment of this application is shown. It is an example and not a limitation. The method for determining the parameters of a toroidal inductor includes steps S101, S102, S103, S104 and S105.

[0067] S101. Determine the target inductance under various current conditions based on the target electrical parameters of the buck-boost converter 101. The target electrical parameters include the target ripple current.

[0068] It is understandable that the target inductance is the inductance of the toroidal inductor that needs to be determined, which is closely related to the parameters of the toroidal inductor, while the target ripple current refers to the maximum ripple current of the toroidal inductor L in the buck-boost converter 101.

[0069] S102. Obtain the core parameters of the initial core of the toroidal inductor, and determine the number of turns of the toroidal inductor based on the core parameters and the target electrical parameters.

[0070] Understandably, the parameters of a toroidal inductor generally include core parameters, the number of turns, and wire diameter. Core parameters are inherent to the core material itself, including its material designation, DC bias, and permeability. Only by determining the core parameters can the corresponding number of turns be determined based on the target electrical parameters; for the same target electrical parameters, different core parameters correspond to different number of turns. Therefore, the initial core selection can be made based on the actual situation, and once the initial core is determined, its corresponding core parameters can be directly obtained.

[0071] S103. Calculate the wire diameter based on the number of turns of the toroidal inductor, and calculate the initial inductance based on the core parameters, number of turns, and wire diameter of the toroidal inductor.

[0072] Understandably, once the core parameters, number of turns, and wire diameter of the toroidal inductor are determined, all the parameters of the toroidal inductor are known. At this point, it is necessary to verify them to determine whether the toroidal inductor meets the requirements. The most important criterion is whether the inductance value meets the target inductance value; therefore, it is necessary to calculate the inductance value of the initially selected toroidal inductor, i.e., the initial inductance value.

[0073] S104. Obtain the difference between the initial inductance and the target inductance. When the difference meets the preset difference, obtain the ripple current of the toroidal inductor under different operating conditions of the buck-boost converter.

[0074] Understandably, since the initial inductance value is generally not exactly the same as the target inductance value, a preset difference is set here, which is the error between the initial inductance value and the target inductance value. Generally, the initial inductance value is required to be greater than or equal to the target inductance value. After confirming that the initial inductance value meets the target inductance value, the ripple current of the toroidal inductor under different operating conditions of the buck-boost converter is calculated.

[0075] S105. When all ripple currents meet the target ripple current of the buck-boost converter, the toroidal inductor is used as the target toroidal inductor.

[0076] It is understandable that the target toroidal inductor must meet the target ripple current of the buck-boost converter. Therefore, all the ripple currents obtained in step S104 must meet the target ripple current of the buck-boost converter in order for the toroidal inductor to be used as the target toroidal inductor.

[0077] In some embodiments, the target electrical parameter includes:

[0078] One or more of the following: input voltage range, maximum input current, maximum charging power, output voltage range, maximum charging current, or switching frequency.

[0079] It is understood that these parameters are all conventional parameters for the buck-boost converter 101 during operation. In the following embodiment, the buck-boost converter 101 includes two inputs, and the target electrical parameters involved are exemplified as follows:

[0080] The input voltage range is 10V to 60V;

[0081] If the maximum input current is 60A, then the maximum input current for each channel is 30A.

[0082] If the maximum charging power is 1000W, then the maximum charging power of each channel is 500W.

[0083] The output voltage range is 40V to 60V;

[0084] The maximum charging current is 25A;

[0085] The switching frequency is 50kHz;

[0086] The target ripple current is 10A.

[0087] Here, the target ripple current can be set according to actual needs.

[0088] See Figure 3 In step S101, the target inductance under various currents is determined based on the target electrical parameters of the buck-boost converter, which may include steps S1011 and S1012.

[0089] S1011. Based on the input voltage range and the output voltage range, calculate the inductance corresponding to the target output ripple current and the inductor current flowing through the inductor in both boost conversion mode and buck conversion mode of the buck converter.

[0090] S1012. Obtain the maximum value of the inductance under the same inductor current, and use the maximum value as the target inductance.

[0091] It is understandable that, in the above steps, the buck-boost converter 101 has at least a boost conversion mode and a buck conversion mode. To meet the inductance requirements of these two operating modes, it is necessary to calculate the inductance corresponding to the target output ripple current and the inductor current flowing through the inductor in both boost and buck conversion modes. Then, assuming the inductor current flowing through the inductor is consistent across both operating modes, the corresponding inductance values ​​are compared. The inductance value of the operating mode with the larger value is selected as the target inductance value.

[0092] It is important to note that when selecting the input and output voltages, the input voltage should be lower than the output voltage in boost conversion mode, while the input voltage should be higher than the output voltage in buck conversion mode. Generally, you can select any combination of the maximum input voltage, minimum input voltage, maximum output voltage, and minimum output voltage. Alternatively, you can add input and output voltages under other more demanding operating conditions to calculate the target inductance and the corresponding average inductor current (i.e., the inductor current flowing through the inductor) under those operating conditions.

[0093] Here, the formula for calculating the inductance corresponding to the target output ripple current is as follows:

[0094]

[0095] Among them, L min This refers to the minimum inductance corresponding to the target output ripple current, V. o This refers to the selected output voltage, where D is... Figure 1 The duty cycle corresponding to switching transistors Q1 to Q4, f s It means Figure 1 The switching frequencies corresponding to transistors Q1 to Q4 in the middle, I w This refers to the target ripple current.

[0096] In boost converter mode, the duty cycle D is calculated using the following formula:

[0097]

[0098] Among them, V in This refers to the selected input voltage.

[0099] In buck converter mode, the duty cycle D is calculated using the following formula:

[0100]

[0101] Taking one input channel and a target ripple current of 10A as an example, the following example is provided:

[0102] In boost converter mode, the three selected input voltages and output voltages are as follows: 1) Input voltage 30V, output voltage 60V; 2) Input voltage 20V, output voltage 40V; 3) Input voltage 16.7V, output voltage 40V.

[0103] In case 1), the inductance calculated by substituting into the above formula is 30μH, and the corresponding inductor current flowing through the inductor is: 500W / 30V = 16.6A.

[0104] In case 2), the inductance calculated by substituting into the above formula is 20μH, and the corresponding inductor current flowing through the inductor is: 500W / 20V = 25A.

[0105] In case 3), the inductance calculated by substituting into the above formula is 19.456μH, and the corresponding inductor current flowing through the inductor is: 500W / 16.7V = 30A.

[0106] In buck converter mode, the selected input voltage is 60V and the output voltage is 40V.

[0107] Substituting into the above formula, the calculated inductance is 26.667μH, and the corresponding inductor current flowing through the inductor is: 500W / 40V = 12.5A.

[0108] Based on the principle that a larger inductor current corresponds to a smaller inductance, it can be concluded that, for the same inductor current, the inductance in boost converter mode is greater than that in buck converter mode. Therefore, the target inductance requirements are: an inductance of 30μH corresponds to an inductor current of 16.6A; and an inductance of 19.456μH corresponds to an inductor current of 30A.

[0109] See Figure 4 In some embodiments, to provide a method for determining the number of turns of a toroidal inductor based on core parameters and target electrical parameters, step S102, which determines the number of turns of the toroidal inductor based on core parameters and target electrical parameters, may include steps S1021 and S1022.

[0110] S1021. Based on the core parameters and target electrical parameters, obtain the mapping relationship table between the loss and number of turns of the toroidal inductor.

[0111] S1022. Determine the number of turns of the toroidal inductor based on the mapping relationship table between losses and turns.

[0112] It is understandable that in the above steps, the toroidal inductor itself has losses, and there is a mapping relationship between losses and the number of turns. To reduce errors, it is necessary to choose the number of turns corresponding to lower losses. Therefore, a mapping relationship table between the losses and the number of turns of the toroidal inductor can be obtained, and the number of turns of the toroidal inductor can be determined according to this mapping relationship table.

[0113] See Figure 5 In some embodiments, to provide a method for determining the mapping relationship between the loss and the number of turns of a toroidal inductor based on the core parameters and the target electrical parameters, step S1021, which determines the mapping relationship between the loss and the number of turns of the toroidal inductor based on the core parameters and the target electrical parameters, may include steps S1021A, S1021B, S1021C, S1021D, and S1021E.

[0114] S1021A, Obtain the preset window coefficient.

[0115] S1021B: Calculate the copper loss of the wires on the toroidal inductor at different numbers of turns based on the preset window coefficient, core parameters, and target electrical parameters.

[0116] S1021C: Calculate the magnetic loss of the magnetic core at different numbers of turns based on the core parameters and target electrical parameters.

[0117] S1021D: Calculate the sum of copper loss and magnetic loss to obtain the loss of the toroidal inductor.

[0118] S1021E. Based on copper loss, magnetic loss, and total loss, determine the mapping relationship table between loss and number of turns.

[0119] Understandably, the losses of a toroidal inductor are generally divided into magnetic losses and copper losses. Magnetic losses refer to the losses of the magnetic core itself, while copper losses refer to the losses caused by the parasitic resistance on the inductor coil.

[0120] Since the window of the magnetic core cannot be 100% utilized, there is a window coefficient, which generally ranges from 0.3 to 0.4.

[0121] The following details how to calculate copper loss and magnetic loss.

[0122] The window factor K of the initial magnetic core selection u Taking a value of 0.4 as an example, the formula for calculating the copper loss of the initially selected magnetic core is as follows:

[0123]

[0124] Among them, P culossThis refers to copper loss in boost converter mode; P out This refers to output power; V in This refers to the input voltage; V o This refers to the output voltage; f s This refers to the switching frequency; N t This refers to the number of turns; A w This refers to the window area; l w This refers to the average length of each turn of wire wound on the magnetic core; e This refers to the effective magnetic circuit length; A L This refers to the inductance coefficient; %u refers to the percentage by which the current permeability changes to its initial permeability; ρ cu_100c This refers to the resistivity of copper at 100℃, typically taken as 0.233 × 10⁻⁶. -7 Ω·m; ΔI boost η refers to the inductor ripple current in boost converter mode; η refers to the efficiency that the designed buck-boost converter needs to achieve, in this example η = 0.95.

[0125] The formula above calculates the loss (i.e., copper loss) on the toroidal inductor wire. This refers to the loss caused by the DC current of the inductor passing through the parasitic resistance of the conductor, while This refers to the loss generated by the AC component of the inductor current in the parasitic resistance of the conductor. The sum of the two losses is the total copper loss in the inductor conductor.

[0126] Here, ΔI boost The calculation formula is:

[0127]

[0128]

[0129] Among them, L bias It refers to the inductance after DC bias, I in.boost This refers to the input current of the buck-boost converter in Boost mode.

[0130] I in.boost The calculation formula is:

[0131]

[0132] And %u, l w and l e These are also fixed parameters inherent to the magnetic core's own model.

[0133] For example, in some magnetic cores, A e =0.331cm 2 , l e = 5.67cm, V e=1.88cm 3 , OD=23.62mm, ID=13.39mm, HT=8.38mm;

[0134]

[0135] l w =[(OD-ID)+2·HT]·1.2=0.032m;

[0136] For a 60u magnetic core, a = 94.1753, b = 146.0936, c = 2.1489, d = 4.8885, A L =43nH.

[0137] For a 75u magnetic core, a = 99.2911, b = 106.2414, c = 1.7476, d = 1.5656, A L =54nH.

[0138] For a 90u magnetic core, a = 99.6613, b = 85.3248, c = 1.7475, d = 1.3639, A L =65nH.

[0139] The formula for calculating magnetic loss is:

[0140]

[0141] Among them, P coreloss This refers to the magnetic loss in boost converter mode, Ve refers to the effective core magnetic circuit volume, Ae refers to the cross-sectional area of ​​the core, magnets refers to the type of core, and P... cv This refers to the magnetic loss per unit volume of the magnetic core, ΔB boost This refers to the magnetic flux density swing in Boost mode.

[0142] Here, ΔB boost The calculation formula is:

[0143]

[0144] And P cv These are fixed parameters inherent to the magnetic core's own model.

[0145] The loss of a toroidal inductor is the sum of the calculated magnetic loss and copper loss, and its calculation formula is as follows:

[0146] P inductor (V in V o ,P out ,f s N t A e Aw ,l w ,l e V e ,K u A L ,%u,magnets)=

[0147] P culoss (V in V o ,P out ,f s N t A w ,l w ,l e ,K u A L ,%u)+P coreloss (V in V o ,f s N t A e V e (magnets);

[0148] Among them, P inductor This refers to the loss of a toroidal inductor.

[0149] Then, based on the calculated magnetic loss, copper loss, and total loss of the toroidal inductor, a mapping table between loss and number of turns is determined.

[0150] The mapping table can be viewed graphically. Figure 6 , where the horizontal axis represents the number of coil turns Nt, and the vertical axis represents the loss of the toroidal inductor.

[0151] Curve A represents:

[0152] V in It is 16.6V, V o 60V, P out 500W·η, f s At 50kHz, the loss P of the toroidal inductor made with the initial magnetic core is... inductor The mapping relationship curve between the number of turns Nt and the number of turns.

[0153] Curve B represents:

[0154] V in 30V, V o 60V, P out 500W·η, f s At 50kHz, the loss P of the toroidal inductor made with the initial magnetic core is... inductor The mapping relationship curve between the number of turns Nt and the number of turns.

[0155] See Figure 6 It is evident that the loss is relatively low when the number of coil turns is between 10 and 30. To ensure the inductance (the smaller the number of turns, the smaller the inductance), this embodiment selects 27 turns, i.e., N. t =27.

[0156] See Figure 7 In some embodiments, since there are multiple choices for the magnetic core of the toroidal inductor, in order to select a suitable initial magnetic core, the parameter determination method of the toroidal inductor may also add steps S102A, S102B and S102C before step S102.

[0157] S102A: Obtain the core parameters of each magnetic core.

[0158] S102B: Obtain the DC bias resistance capability of each magnetic core under the same parameters.

[0159] S102C: The core with the greatest resistance to DC bias is selected as the initial core.

[0160] Understandably, the DC bias resistance of each magnetic core can be obtained by calculating and plotting the DC bias curve of each magnetic core.

[0161] See Figure 8 In some embodiments, to illustrate in detail how to calculate the wire diameter based on the number of turns of the toroidal inductor, step S103 may include steps S1031, S1032 and S1033.

[0162] S1031. Obtain the window area of ​​the core of the toroidal inductor.

[0163] S1032, Obtain the preset window coefficient.

[0164] S1033. Calculate the wire diameter based on the window coefficient, window area, and number of turns.

[0165] As can be understood from the above embodiments, the window area A of the magnetic core... w and window coefficient K u All parameters are known after the magnetic core is determined, therefore they can be determined based on the window coefficient K. u Window area A w and number of turns N t Calculate the wire diameter.

[0166] The formula for calculating wire diameter is:

[0167]

[0168] Where d refers to the wire diameter.

[0169] Once the initial magnetic core is selected, the wire diameter d can be calculated to be 2.007mm based on the relevant parameters of the initial magnetic core. Therefore, two wires with a diameter of 2.0mm are selected and wound around the magnetic core.

[0170] In some embodiments, in step S103, the DC bias is generally considered when calculating the inductance, so the calculation formula can be:

[0171] L(i,N t ,l e A L ) = N t 2 ·A L ·%u(i,N t ,l e 1%

[0172] Where L refers to the inductance; i refers to the inductor current flowing through the inductor; N t This refers to the number of turns; l e This refers to the effective magnetic circuit length; A L This refers to the inductance coefficient, a core parameter; %u(i,N) t ,l e () refers to the percentage by which the current permeability changes to the initial permeability.

[0173] Because a toroidal inductor with the same inductance current and number of turns will have different inductance values ​​depending on its initial permeability.

[0174] See Figure 9 This is a schematic diagram showing the relationship between the inductance and the inductor current flowing through the magnetic core with two initial permeability values. The horizontal axis represents the inductor current flowing through the inductor, and the vertical axis represents the inductance. Curve C represents the relationship between the inductance and inductor current of the magnetic core with an initial permeability of 90, and curve D represents the relationship between the inductance and inductor current of the magnetic core with an initial permeability of 60.

[0175] It is evident that a magnetic core with an initial permeability of 90 has a larger inductance, making it easier to meet the minimum inductance value (i.e., the target inductance value) required by a buck-boost converter.

[0176] The inductance of a magnetic core with an initial permeability of 90 is calculated under different inductor currents (substituted into the inductor current required for the target inductance), as follows:

[0177] L bias (0A,N t ,l e A L "nps90u") = 87.267 μH;

[0178] L bias (16.6A,Nt ,l e A L "nps90u") = 42.85 μH;

[0179] L bias (30A,N t ,l e A L "nps90u") = 24.059 μH;

[0180] Referring to the above embodiments, the target inductance requirements are: an inductance of 30μH with an inductance current of 16.6A; and an inductance of 19.456μH with an inductance current of 30A. It is evident that, for the same inductance current, the calculated inductance is greater than the target inductance, thus meeting the requirements.

[0181] In addition, in step S104, the ripple current of the toroidal inductor under different operating conditions of the buck-boost converter is obtained. The ripple current refers to the AC quantity of the DC inductor current, which can be calculated using a formula.

[0182] The formula for calculating inductor current is:

[0183] I inductor (V in V o ,P out ,f s N t ,l e A L ,%u,t)=

[0184] I mos (V in V o ,P out ,f s N t ,l e A L ,%u,t)+I diode (V in V o ,P out ,f s N t ,l e A L ,%u,t);

[0185] Among them, I inductor I refers to the inductance current when the toroidal inductor is working. mos It refers to the inductor current I when the switching transistor is turned on. diode This refers to the inductor current when the switching transistor is off and the diode freewheels; t refers to the time variable. mos and Idiode It can be obtained directly through the corresponding current sensor.

[0186] In some embodiments, if the difference calculated in step S104 does not meet the preset difference, or if there is a ripple current in step S105 that does not meet the target ripple current, then refer to... Figure 10 The method for determining the parameters of the toroidal inductor may further include step S104A, or see [reference needed]. Figure 11 The method for determining the parameters of the toroidal inductor may further include step S104B.

[0187] S104A. If the difference does not meet the preset difference or the ripple current does not meet the target ripple current, replace the initial magnetic core and execute step S102.

[0188] S104B: If the difference does not meet the preset difference, or if the ripple current does not meet the target ripple current, change the number of turns of the toroidal inductor and execute step S103.

[0189] It is understandable that the purpose of the above steps S104A and S104B is to replace the initial magnetic core or change the number of turns of the toroidal inductor and recalculate and determine the parameters when the calculated inductance value does not match the target inductance value or the calculated ripple current does not match the target ripple current.

[0190] The purpose of setting a preset difference is that the calculated inductance may be much larger than the target inductance. For example, the inductance calculated in the above embodiment is much larger than the target inductance. Therefore, in order to reduce costs, a magnetic core with a smaller outer diameter, inner diameter, and thickness can be selected and the above calculations and parameter determinations can be performed again.

[0191] In addition, in some embodiments, the parameter determination method may include the following steps:

[0192] Construct a toroidal inductor based on the target toroidal inductor;

[0193] Calculate and obtain the inductor current waveform corresponding to the target inductance;

[0194] Obtain test data of the toroidal inductor under actual working conditions. The test data includes the test inductor current waveform under different working modes when the toroidal inductor is placed under actual working conditions.

[0195] Compare the test data with the inductor current waveform corresponding to the target inductance;

[0196] If the comparison result is satisfactory, then the parameters of the target toroidal inductor are the parameters of the final toroidal inductor obtained.

[0197] If the comparison result is not qualified, replace the initial magnetic core and proceed to step S102; or change the number of turns of the toroidal inductor and proceed to step S103.

[0198] To prevent the coil from melting, in some embodiments, step S103, after calculating the wire diameter, may further include the following method for determining the parameters of the toroidal inductor:

[0199] Calculate the maximum current density of the toroidal inductor based on the wire diameter and target electrical parameters.

[0200] When the maximum current density is greater than the preset maximum current density, change the initial core selection and / or change the number of turns.

[0201] As we understand it, current density refers to the amount of current flowing through a unit area of ​​conductor. The higher the current density, the greater the temperature rise of the conductor. The magnetic core and coil each have their own temperature limits; exceeding these limits will cause melting and damage to the insulation material. Therefore, limiting the maximum current density can prevent melting of the coil and other components. The preset maximum current density can be set according to actual needs; for example, a higher preset maximum current density can be used when heat dissipation is good. The preset maximum current density is generally set between 2 and 6.

[0202] The formula for calculating the maximum current density is as follows:

[0203]

[0204] Among them, K j This refers to current density, i max This refers to the maximum inductance current flowing through a toroidal inductor.

[0205] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0206] The toroidal inductor provided in the second aspect of the embodiments of this application is applied to the above-mentioned buck-boost converter 101. The toroidal inductor is designed and manufactured according to the above-mentioned method for determining the parameters of the toroidal inductor.

[0207] The buck-boost converter provided in the third aspect of this application includes a toroidal inductor as described above, and its structural schematic diagram can be found in [reference needed]. Figure 1 .

[0208] It should be noted that the information interaction and execution process between the above-mentioned devices / units / modules are based on the same concept as the method embodiments of this application. For details on their specific functions and technical effects, please refer to the method embodiments section, and they will not be repeated here.

[0209] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0210] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of this application can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include at least: any entity or device capable of carrying the computer program code to a photographing device / terminal device, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium. Examples include USB flash drives, portable hard drives, magnetic disks, or optical disks. It should be noted that the content contained in the computer-readable medium may be appropriately added to or subtracted from the content as required by the legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium may not include electrical carrier signals and telecommunication signals.

[0211] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0212] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0213] In the embodiments provided in this application, it should be understood that the disclosed apparatus / network devices and methods can be implemented in other ways. For example, the apparatus / network device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0214] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0215] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

[0216] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for determining the parameters of a toroidal inductor, characterized in that, The parameter determination method includes: The target inductance under various current conditions is determined based on the target electrical parameters of the buck-boost converter, including the target ripple current. Obtain the core parameters of the initial core of the toroidal inductor, and determine the number of turns of the toroidal inductor based on the core parameters and the target electrical parameters; The wire diameter is calculated based on the number of turns of the toroidal inductor, and the initial inductance is calculated based on the core parameters, the number of turns, and the wire diameter of the toroidal inductor. The difference between the initial inductance and the target inductance is obtained. When the difference satisfies the preset difference, the ripple current of the toroidal inductor under different operating conditions of the buck-boost converter is obtained. When all the ripple currents meet the target ripple current of the buck-boost converter, the toroidal inductor is used as the target toroidal inductor. The target electrical parameters also include the input voltage range and the output voltage range. Determining the target inductance under various current conditions based on the target electrical parameters of the buck-boost converter includes: Based on the input voltage range and the output voltage range, calculate the inductance and inductor current corresponding to the target ripple current output by the buck-boost converter in buck conversion mode and buck conversion mode, respectively; obtain the maximum value of the inductance under the same inductor current, and use the maximum value as the target inductance.

2. The method for determining the parameters of a toroidal inductor as described in claim 1, characterized in that, Determining the number of turns of the toroidal inductor based on the core parameters and the target electrical parameters includes: Based on the core parameters and the target electrical parameters, obtain a mapping table between the loss and the number of turns of the toroidal inductor; The number of turns of the toroidal inductor is determined according to the mapping table between losses and the number of turns.

3. The method for determining the parameters of a toroidal inductor as described in claim 2, characterized in that, The step of determining the mapping relationship table between the loss and the number of turns of the toroidal inductor based on the core parameters and the target electrical parameters includes: Get the preset window coefficient; Calculate the copper loss of the wires on the toroidal inductor at different numbers of turns based on the preset window coefficient, the magnetic core parameters, and the target electrical parameters; Calculate the magnetic loss of the magnetic core at different numbers of turns based on the magnetic core parameters and the target electrical parameters; The loss of the toroidal inductor is obtained by calculating the sum of the copper loss and the magnetic loss. Based on the copper loss, the magnetic loss, and the total loss, a mapping table between the loss and the number of turns is determined.

4. The method for determining the parameters of a toroidal inductor as described in claim 1, characterized in that, The target electrical parameters include: One or more of the following: input voltage range, maximum input current, maximum charging power, output voltage range, maximum charging current, switching frequency, or target ripple current.

5. The method for determining the parameters of a toroidal inductor as described in claim 1, characterized in that, The parameter determination method further includes: Obtain the core parameters for each magnetic core; To obtain the DC bias resistance capability of each magnetic core under the same parameters; The magnetic core with the greatest resistance to DC bias is selected as the initial magnetic core.

6. The method for determining the parameters of a toroidal inductor as described in claim 5, characterized in that, The parameter determination method further includes: If the difference does not meet the preset difference, or if there is a ripple current that does not meet the target ripple current, the initial magnetic core is replaced, and the steps of obtaining the magnetic core parameters of the initial magnetic core of the toroidal inductor and determining the number of turns of the toroidal inductor based on the magnetic core parameters and the target electrical parameters are executed. Alternatively, if the difference does not meet the preset difference, or if there is a ripple current that does not meet the target ripple current, the number of turns of the toroidal inductor is changed, and the steps of calculating the wire diameter based on the number of turns of the toroidal inductor and calculating the initial inductance based on the core parameters, the number of turns, and the wire diameter are performed.

7. The method for determining the parameters of a toroidal inductor as described in any one of claims 1-6, characterized in that, The calculation of wire diameter based on the number of turns of the toroidal inductor includes: Obtain the window area of ​​the magnetic core of the toroidal inductor; Get the preset window coefficient; The wire diameter is calculated based on the window coefficient, the window area, and the number of turns.

8. The method for determining the parameters of a toroidal inductor as described in claim 1, characterized in that, The parameter determination method further includes: Calculate the maximum current density of the toroidal inductor based on the wire diameter and the target electrical parameters; When the maximum current density is greater than the preset maximum current density, the initial magnetic core is changed and / or the number of turns is changed.

9. A toroidal inductor used in a buck-boost converter, characterized in that, The toroidal inductor is designed and manufactured according to the parameter determination method as described in any one of claims 1 to 8.

10. A buck-boost converter, characterized in that, Including the toroidal inductor designed and manufactured using the parameter determination method as described in any one of claims 1 to 8.

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